[SciPy-user] dgemm overwrite_c bug?
Dan Goodman
dg.numpy@thesamovar....
Wed Aug 27 21:03:45 CDT 2008
Hi all,
I'm interesting in doing a matrix multiplication in-place, and because
numpy's dot function doesn't do that I had to go looking. After much pain
I finally found the linalg.blas etc. stuff in scipy. However, I think that
the dgemm function is ignoring the overwrite_c parameter, e.g.:
from numpy import array
from scipy import linalg
gemm, = linalg.blas.get_blas_funcs(['gemm'])
x=array([[1.,2.],[3.,4.]])
y=array([[5.,6.],[7.,8.]])
c=array([[8.,9.],[10.,11.]])
print gemm(1.0,x,y,1.,c,0,0,overwrite_c=1)
print
print c
gives the output
[[ 27. 31.]
[ 53. 61.]]
[[ 8. 9.]
[ 10. 11.]]
but the two matrices ought to be the same...
Or have I misunderstood something? There seems to be a lack of documentation
for these functions, so that's quite possible.
Is there any way of getting access to an in-place matrix multiplication
like this?
Many thanks,
Dan Goodman
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